1. Field of the Invention
This invention is directed to a flexible, folding agricultural implement, such as a cultivator-planter, and, more particularly, to such an implement which includes a number of individual frame sections linked to each other via flexible connector links, each of which includes a limit stop which limits the amount of relative twist between adjacent frame sections. The limit stops help to prevent implement roll-over in extreme terrain conditions and also allow the flexible connector links to double as pivot arms as the outer frame sections are folded to narrow the implement for transport.
2. Description of the Related Art
With increasing demand for world-wide food production, agricultural operations have expanded from traditional level terrain to encompass more and more difficult and marginal terrain. Terracing has become more common, even on large scale wheat and soybean farming operations. Combined with this trend is the use of larger and larger tractors, allowing ever wider towed implements to be developed to reduce the time and labor needed for crop planting and cultivating.
However, traditional towed implements, such as cultivators, seeders and discs, have generally used rigid steel frames supported by wheels which are selectively movable up and down relative to the frame to set operating depths for the ground working tools on the implement. The entire frame is thus set at a given, uniform spacing above the wheels. This system works generally satisfactory as long as the terrain is reasonably level or when the implement frame is fairly narrow. However, as the terrain becomes rougher, with man-made terraces and natural undulations, and as implements become wider, the traditional system of having a rigid frame extending the width of the implement with a uniform spacing between frame and wheels is no longer effective. This is because, with the wide rigid frame and undulating terrain, some wheels may actually leave ground contact, lifting their associated working implements such as discs, tines and seed drills, etc. to too shallow a depth for effective ground working. In extreme terrain, some implements may be even lifted entirely out of the ground. This can cause uneven and intermittent cultivation of the soil and or planting of the crop.
A number of attempts have been made to construct a flexible agricultural implement which more closely follows undulations in terrain. One such attempt is reflected in U.S. Pat. No. 3,841,312 to Sosalla. The Sosalla patent teaches a cultivator with multiple wing sections which are hinged connected together along generally horizontal axes. This arrangement allows the wings to pivot in two dimensions relative to each other about the hinges to follow the ground contour. The Sosalla implement is folded by rotating each wing about a horizontal axis and pivoting the outer wings backward to ride on dedicated wheels.
Another attempt to make a flexible implement is found in U.S. Pat. No. 4,790,389 to Raymond Adee and assigned to Flex-King Corporation. In the Adee patent, a field cultivator frame is made of multiple frame sections, with four such sections illustrated. The two center most frame sections are interconnected via a flex link which allows each half of the implement frame to twist up or down somewhat relative to the other half. The two outermost frame sections are attached to the adjacent center section via a hinge which allows them to pivot relative to that center section but not to twist up or down. The two outermost frame sections can be folded 90 degrees relative to respective center sections via a pair of folding piston & cylinder units which pivot the outermost frame sections upward about the hinge connection. Thus, due to the requirement for folding outer frame sections, in the Adee patent only the connection between center frame sections is allowed to twist.
Prior art flexible implements thus suffer from a number of shortcomings. No implement has been devised which allows multiple frame sections to twist up and down relative to each adjacent section while also allowing the sections to be folded for transport. This is because, up to now, no flexible connection system has been devised which allows the flexibility required of a twisting system yet provides a stable pivot arm and axis such that the frame sections can be folded. This presents a significant limitation on the width of the implement and/or the flexibility of the implement since the greater the number of independent sections, the more closely the implement can follow the ground contour. Another problem is that the conventional direct and rigid connection of the implement hitch to the front of the implement frame does not allow forward and rearward tilting of the hitch relative to the frame.
It is clear then, that a need exists for a flexible agricultural implement which can follow the contour of relatively uneven terrain, while maintaining substantially even depth of individual tillage implements across the width and fore and aft length of the implement. Such an implement should be constructed of up to seven sections which are flexibly attached to one another, yet which can be folded to a width substantially equal to three of the sections.